Along with increasing innovation and development in the illumination industry, and increasing importance of energy savings, light-emitting diode (LED) lighting technology is developing fast as a revolutionary lighting technology. Because the luminance of LEDs is related to the luminous intensity, which is proportional to the current and forward voltage of LEDs, and may change due to temperature variation, a constant current source may be utilized for driving LEDs. Thus, to achieve a good reliability and a good luminous intensity, an appropriate LED driver is an important part of the overall design. Without a good LED driver, inherent advantages of LED technology may not be fully realized.